1. Field of Invention
The present invention relates to a method for driving a display device that reduces the power consumption by placing only a pixel belonging to a specific data line into a display state, while placing pixels belonging to other data lines into a non-display state.
2. Description of Related Art
In display devices used in portable electronic apparatus, such as portable telephones, the number of display dots has rapidly increased so that more information can be displayed. On the other hand, since portable electronic apparatuses are battery driven in principle, there exists a strong desire to reduce their power consumption. For this reason, the display device used in the portable electronic apparatus is required to have two apparently contradictory features of high resolution and low power consumption.
Thus, in order to solve such a problem, the following driving method called a partial display driving (also referred to as a partial driving) has been proposed. That is, in the partial display driving, when a full-screen display operation is not particularly required, such as during standby, scanning signals are supplied only to a part of scanning lines, whereby only a region of pixels belonging to the part of the scanning lines is put into a display state, while other regions of pixels are put into a non-display state, as shown in FIG. 26 to suppress the power consumption.
According to the partial display driving, however, a display region (non-display region) is necessarily long sideways in accordance with a direction of formation of scanning lines, so that a display mode in the partial display is restricted in this sense. Nevertheless, when a display operation is performed in which a display region is long lengthways, with a configuration in which a non-lighting voltage is simply supplied to data lines included in a non-display region, a switching frequency of the voltage applied to the data lines is not decreased, so that the power consumption is not effectively reduced.